Method of manufacturing a multifilament superconductor with resistive barrier integrated into the outer ring

Abstract

The invention concerns a method of making a superconductor so that it includes, in cross-section: a central area, made up of a plurality of superconductor filaments of the NbTi, NbTiTa type or of any other alloy or substance based on Nb; a concentric, two part, outer ring surrounding the central area; and a concentric resistive barrier. In accordance with the invention, the concentric resistive barrier is integrated into the concentric outer ring.

We claim: 
     
       1. Method of manufacturing a superconductor (1), having a copper outer ring (4), in N drawing stages comprising: performing N-1 successive stages of billeting and drawing to manufacture a multifilament superconductor of a substance based on Nb;   performing an Nth stage of forming the superconductor to the final size, which includes: disposing a distal hollow cylinder (6) coaxially with an intermediate hollow cylinder (5) and a proximal hollow cylinder (7) to thereby constitute a composite hollow cylinder (14), wherein said distal hollow cylinder (6) and said proximal hollow cylinder (7) are made from the same material as the outer ring, and said intermediate cylinder is made of a resistive barrier material;   filling said composite hollow cylinder (14) in an ordered manner with rods (15), obtained from the multifilament superconductor (13) obtained from the (N-1)th stage of the method, to produce a billet;   closing the ends of the billet and evacuating the interior of the billet; and   drawing the billet to the required diameter of the superconductor (1).     
     
     
       2. Method according to claim 1, further comprising choosing the thicknesses of the hollow cylinders (5, 6, 7) so that, after drawing, the superconductor (1) has a resistive barrier having a predetermined thickness and a predetermined location in the outer ring (4). 
     
     
       3. Method according to claim 1, further comprising choosing the thicknesses of the hollow cylinders (5, 6, 7), and choosing the composition of the resistive barrier material of intermediate hollow cylinder (5) so as to obtain a predetermined ratio of the losses between superconductors to the losses between the filaments. 
     
     
       4. Method according to any one of claims 1 to 3, further comprising choosing the thicknesses of the hollow cylinders (5, 6, 7), and choosing the composition of the resistive barrier material of intermediate hollow cylinder (5) so as to obtain a predetermined residual resistance ratio (RRR). 
     
     
       5. Method according to claim 2, further comprising choosing the thicknesses of the hollow cylinders (5, 6, 7), and choosing the composition of the resistive barrier material of intermediate hollow cylinder (5) so as to obtain a predetermined ratio of the losses between superconductors to the losses between the filaments. 
     
     
       6. Method according to claim 5, further comprising choosing the thicknesses of the hollow cylinders (5, 6, 7), and choosing the composition of the resistive barrier material of intermediate hollow cylinder (5) so as to obtain a predetermined residual resistance ratio (RRR). 
     
     
       7. A method of manufacturing a superconductor, comprising: disposing a distal hollow cylinder, which has a first diameter, coaxially with an intermediate hollow cylinder and a proximal hollow cylinder to thereby form a composite hollow cylinder, wherein said distal hollow cylinder and said proximal hollow cylinder are both made from a first material, and said intermediate cylinder is made of a resistive barrier material;   filling said composite hollow cylinder with multifilament superconductor rods, to produce a billet;   closing the ends of the billet and evacuating the interior of the billet; and   drawing the billet to a second diameter which is smaller than said first diameter.   
     
     
       8. Method according to claim 7, wherein said first material is copper. 
     
     
       9. Method according to claim 7, wherein said multifilament superconductor rods include Nb. 
     
     
       10. Method according to claim 9, wherein said multifilament superconductor rods include Cu. 
     
     
       11. Method according to claim 7, wherein said multifilament superconductor rods are hexagonal in cross section. 
     
     
       12. Method according to claim 7, further comprising choosing the thicknesses of the hollow cylinders so that, after drawing, the superconductor has a resistive barrier having a predetermined thickness and a predetermined location with respect to said second diameter. 
     
     
       13. Method according to claim 7, further comprising choosing the thicknesses of the hollow cylinders, and choosing the composition of the resistive barrier material of intermediate hollow cylinder so as to obtain a predetermined ratio of the losses between superconductors to the losses between the filaments. 
     
     
       14. Method according to claim 7, further comprising choosing the thicknesses of the hollow cylinders, and choosing the composition of the resistive barrier material of intermediate hollow cylinder so as to obtain a predetermined residual resistance ratio (RRR).